Slide Rules and Generations

America sent three astronauts to the moon in July of 1969. Neil Armstrong, Buzz Aldrin and Michael Collins took off from the Kennedy Space Center in central Florida in a huge rocket with miles of wires and tons of explosive liquids in an impressive column of fire and smoke. Watching the Saturn Five launch “in person” was an awesome sight. You not only saw the launch, but you could feel it in your feet and your chest – miles away. Quite the experience, to say the least.

This marvelous vehicle was thirty-three feet in diameter, over three hundred feet tall, and weighed almost three thousand tons. It developed over seven and a half million pounds of thrust in the first stage alone. This was a complete engineering marvel.

It was designed using slide rules, paper and pencils.

While there were computers being used in engineering in the sixties, much of the math was done using the slide rule – a “simple analog computer.” The slide rule was first developed in the seventeenth century, but was rendered obsolete with the advent of the electronic calculator in 1974 – five years after Apollo Eleven. Besides multiplication and division, the slide rule also computes roots and powers, trigonometry, logarithms and exponentials – if you know how to use it.

In 1973, fresh out of high school, I attended a class in conjunction with my job that required the use of algebraic formulas and some pretty intense mathematics. No one in the classroom – all 35-40 years old – could use these formulas or remember any high school math. On the other hand, I brought my good ol’ slide rule from Math Analysis class in my senior year. Using it, I got all the answers and a lot of scowls from my classmates. I carried that slide rule in my equipment for years, and I still have it.

Did you know that each of the Apollo Eleven astronauts carried a slide rule in his spacesuit? So did the Apollo Thirteen astronauts in their ill-fated trip to and from the moon.

If you are over fifty, there is a good chance that you at least tried to use a slide rule at one time or another. But using slide rules taught us was something very valuable – how to estimate the answer in a math problem. Since slide rules don’t provide us with an exact number or the location of the decimal point, we had to come up with a estimated number and decimal without anything more mechanical than a human brain.

We see “younger folks” today who can’t make change for a dollar, figure out percentages or do even the most simple number calculations. Cheap electronic calculators have been around since the seventies and generations have not had to do “mental math.” The skill of “estimation” has been lost.

This past week, I introduced by granddaughter to the slide rule. I showed her some simple multiplication on the C and D scales, and she was amazed. Her father, a pilot, explained how they use specialized slide rules – not calculators – in the cockpit. The point of this exercise with her was not to teach her to use a seventeenth century math tool, but to stress the importance of using the brain without the electronics.

And I think that it worked. Try if on your grandkids.

Tell others!!

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Kevin Duffy is an Associate Professor of Criminal Justice at Daytona State College in Florida and a dedicated car guy. He divides his time between teaching criminal justice topics in the online environment and working on/driving cars, particularly Porsches. Kevin is one of the principals in InspiringLifeOver50.com.